package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.StrUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.dto.ScrollResult;
import com.hmdp.dto.UserDTO;
import com.hmdp.entity.Blog;
import com.hmdp.entity.Follow;
import com.hmdp.entity.User;
import com.hmdp.mapper.BlogMapper;
import com.hmdp.service.IBlogService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.service.IFollowService;
import com.hmdp.service.IUserService;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.SystemConstants;
import com.hmdp.utils.UserHolder;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.ZSetOperations;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

import static com.hmdp.utils.RedisConstants.FEED_KEY;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class BlogServiceImpl extends ServiceImpl<BlogMapper, Blog> implements IBlogService {

    @Resource
    private IUserService userService;

    @Autowired
    private StringRedisTemplate stringRedisTemplate;
    @Autowired
    private IFollowService followService;

    @Override
    public Result queryBlogById(Long id) {
        Blog blog = getById(id);
        if(blog==null){
            return Result.fail("笔记不存在");
        }
        queryBlogUser(blog);
        isBlogLiked(blog);
        return Result.ok(blog);
    }

    @Override
    public Result queryHotBlog(Integer current) {
        // 根据用户查询
        Page<Blog> page = query()
                .orderByDesc("liked")
                .page(new Page<>(current, SystemConstants.MAX_PAGE_SIZE));
        // 获取当前页数据
        List<Blog> records = page.getRecords();
        // 查询用户
        records.forEach(this::queryBlogUser);
        records.forEach(this::isBlogLiked);
        return Result.ok(records);
    }

    @Override
    public Result likeBlog(Long id) {
        Long userId = UserHolder.getUser().getId();
        String key = RedisConstants.BLOG_LIKED_KEY + id;
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        if(null == score){
            boolean isSuccess = update().setSql("liked = liked + 1")
                    .eq("id", id).update();
            if(isSuccess){
                stringRedisTemplate.opsForZSet().add(key, userId.toString(), System.currentTimeMillis()); // from small to large
            }
        }else {
            boolean isSuccess = update().setSql("liked = liked - 1")
                    .eq("id", id).update();
            if (isSuccess){
                stringRedisTemplate.opsForZSet().remove(key, userId.toString());
            }
        }
        return Result.ok();

    }

    @Override
    public Result queryBlogLikes(Long id) {
        String key = RedisConstants.BLOG_LIKED_KEY + id;
        Set<String> top5User = stringRedisTemplate.opsForZSet().range(key, 0, 4);
        if(null == top5User || top5User.isEmpty()){
            return Result.ok(Collections.emptyList());
        }
        List<Long> ids = top5User.stream().map(Long::valueOf).collect(Collectors.toList());
        String idStr = StrUtil.join(",", ids);
        // WHERE id IN ( 5 , 1 ) ORDER BY FIELD(id, 5, 1) to keep the order
        List<UserDTO> userDTOS = userService.query()
                .in("id", ids)
                .last("ORDER BY FIELD(id, " + idStr + ")")
                .list()
                .stream()
                .map(user -> BeanUtil.copyProperties(user, UserDTO.class))
                .collect(Collectors.toList());
        return Result.ok(userDTOS);
    }

    @Override
    public Result saveBlog(Blog blog) {
        UserDTO user = UserHolder.getUser();
        blog.setUserId(user.getId());
        boolean success = save(blog);
        if(!success){
            return Result.fail("新增笔记失败");
        }
        List<Follow> followers = followService.lambdaQuery()
                .eq(Follow::getFollowUserId, user.getId())
                .list();
        // 给每个follower推送
        followers.forEach(follower->{
            Long userId = follower.getUserId();
            String key = FEED_KEY + userId;
            stringRedisTemplate.opsForZSet().add(key, blog.getId().toString(), System.currentTimeMillis());
        });
        return Result.ok(blog.getId());
    }

    @Override
    public Result queryBlogOfFollow(Long max, Integer offset) {
        Long userId = UserHolder.getUser().getId();
        String key = FEED_KEY + userId;
        Set<ZSetOperations.TypedTuple<String>> blogTupleSet = stringRedisTemplate.opsForZSet()
                .reverseRangeByScoreWithScores(key, 0, max, offset, 2);
        if(blogTupleSet == null || blogTupleSet.isEmpty()){
            return Result.ok();
        }
        List<Long> ids = new ArrayList<>(blogTupleSet.size());
        long minTime = 0;
        int os = 1;
        for(ZSetOperations.TypedTuple<String> blogTuple : blogTupleSet){
            String blogId = blogTuple.getValue();
            ids.add(Long.valueOf(blogId));
            long time = blogTuple.getScore().longValue();
            if(time == minTime){
                offset++;
            }else {
                minTime = time;
                offset = 1;
            }
        }

        String idStr = StrUtil.join(",", ids);

        List<Blog> blogs = lambdaQuery().in(Blog::getId, ids)
                .last("ORDER BY FIELD(id," + idStr + ")")
                .list();

        for (Blog blog : blogs) {
            queryBlogUser(blog);
            isBlogLiked(blog);
        }

        ScrollResult r = new ScrollResult();
        r.setList(blogs);
        r.setOffset(os);
        r.setMinTime(minTime);
        return Result.ok(r);
    }

    private void queryBlogUser(Blog blog){
        Long userId = blog.getUserId();
        User user = userService.getById(userId);
        blog.setName(user.getNickName());
        blog.setIcon(user.getIcon());
    }

    private void isBlogLiked(Blog blog){
        UserDTO user = UserHolder.getUser();
        if(null == user){
            return;
        }
        Long userId = user.getId();
        String key = RedisConstants.BLOG_LIKED_KEY + blog.getId();
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        blog.setIsLike(null != score);
    }


}
